Marine transfer assembly



NOV. 1952 J. w. WINFREY ETAL 3,064,829

MARINE TRANSFER ASSEMBLY 2 Sheets-Sheet 2 Filed Dec. 10, 1959 INVENTORS.

JAMES w. WINFREY,

RxcHARo P. KNAPP BY ALBERT s. HOVE ATTORNEY.

trite dttes 3,064,829 MARINE TRANSFER ASSEMBLY James W. Winfrey, RichardP. Knapp, and Albert S. Hove, Houston, Tex, assignors, by mesneassignments, to Jersey Production Research (Iompauy, Tuisa, Okla, acorporation of Delaware Filed Dec. 10, 1959, Ser. No. 858,809 4 Claims.(Cl. 214-14) The present invention is directed to a marine transferassembly. More particularly, the invention is concerned with a devicefor transferring personnel and material between a boat and an offshorestructure or between two floating vessels. In its more specific aspects,the invention is concerned with a transfer assembly which allowspersonnel and material to be safely transferred between a vessel andanother structure in troubled waters.

The present invention may be briefly described as a marine transferassembly for a marine structure which comprises a ramp extendingoutwardly from the structure. Arranged vertically below the structure isa guide pipe adapted to contain a body of liquid such as water. Arrangedwithin the guide pipe is a hollow elongated counterweight provided witha valve in its lower end which prevents or restricts liquid flow intothe counterweight when it is moving downwardly in the guide pipe. Thecounterweight is suitably provided with means circumferentially spacedapart thereon for damping downward movement of the counterweight intothe body of liquid. These means may suitably comprise circumferentiallyand vertically spaced-apart fins arranged on the exterior surface of thecounterweight and which are sized and spaced to provide the desireddamping effect. A carriage is provided which is connected by flexiblemeans to the counterweight, the flexible means being arranged overspaced-apart pulleys carried by the structure. The counterweight has aweight such that the effective pull of the counterweight exerted on thecarriage is greater than effective counterpull of the carriage plus anyloading placed thereon such that release of the carriage from arestrained lowered position causes movement upwardly toward the ramp.While the counterweight may be greater than the weight of the carriageplus any loading thereon, the weight of the counterweight may be lessthan that of the carriage and its load depending on the number ofpurchase lines employed. The counterweight is suitably provided of asufiicient weight such that acceleration upwardly is sufficiently rapidto clear the vessel which may be pitching violently. In short, theupward acceleration of the carriage is greater than that of the vessel.The movement upwardly of the carriage, after clearing the vessel, isthen damped by entrance of the counterweight into the body of liquid.

The ramp may suitably be connected to the structure for pivotalhorizontal movement and the carriage is provided with a flexible meanswhich is releasably attached to a vessel in the body of water forpulling the carriage down to the vessel. The flexible means is alsoreleasably attach d to the carriage.

While the ramp may be pivotally attached, it may also be fixedlyarranged connected to the structure and the carriage may be attached toa boom extending outwardly from the structure which pivots in ahorizontal plane to bring the carriage underneath or alongside the ramp.Some structures will not require a ramp. The present invention will befurther illustrated by reference to the drawing in which:

F G. l is an isometric view of a preferred embodiment;

FIG. 2 is another embodiment with the ramp in a fixed position and thecarriage supported on a swivel boom;

FIG. 3 is another view of the swivel boom of FIG. 2;

3&554329 Patented Nov. 20, 1952 FIG. 4 is a sectional view of anembodiment of the guide pipe and counterweight of FIGS. 1 and 2; and

FIG. 5 is a sectional view of a quick release mechanism for disengagingthe carriage from a flexible means.

Referring now to the drawing in which identical numerals will beemployed to designate identical parts, the numeral 11 designates anoffshore structure carried and supported by a plurality of verticallyextending support members 12 which extend to the bottom of a body ofwater 10. It is to be understood that structure 11 may be a mobile orfloating rather than a fixed structure. The support members 12 areinterconnected by braces and truss .work 13 and 14-.

Extending outwardly from the platform 11 is a ramp 15 which is fixed bystructural support means 16 to a corner of support member 12. Arrangedvertically below the offshore structure 11 is a counterweight guide pipe18 in which a counterweight 19, which will be described furtherhereinafter, is supported by wire line or rope 20 by means of a U-bolt21 and eye means 22. The wire line 20 is connected by yoke '23 toparallel wire lines 24 which extend over a pair of pulleys or sheaves 25and over a second pair of pulleys or sheaves 26 adjacent the free end 27of the ramp 15, the wire lines 24 being attached to a carriage 28 whichis suspended from the free end 27 of the ramp. The parallel lines 24may, if desired for safety purposes, be connected directly to thecounterweight 19. The carriage 28 is suitably provided with a ladder 29which allows personnel to climb from within the carriage and, by meansof the corresponding ladder 36, on to the ramp 15. Attached to the lowerend of the carriage 28, by means of a quick release mechanism shown inand described more particularly with reference to FIG. 5, is a rope orline 31 which depends therefrom and which is suitably caught bypersonnel on a crew boat such as 32 and run over a swivel or sheave 33and connected to a Winch or hoisting means 34- operatively connected toa motor or engine 35. The rope or line 31 extends through an opening orport 36 in alanding 37 on the crew boat 32. While this landing 37,preferably fitted with shock-absorbing bumper, is shown preferably onthe stern of the vessel 32, it may also be arranged on the bow thereof.

As shown in PEG. 1, it is necessary to provide shock absorbers such as39 underneath the ramp 15 or on top of carriage 28 or both to lessen theshock of the carriage when it travels upwardly from the crew boat 32 tothe ramp 15.

Referring now to FIGS. 2 and 3, an offshore structure such as 11 issuitably supported by support members 12 and by braces and supportmembers 13 and 14 such as in FIG. 1. In FIG. 2 a counterweight guidepipe 50 is arranged adjacent and attached to one of the support members12 and extends down into the body of water It The guide pipe may beabove water depending on the type of the structure employed. The guidepipe may be inside a caisson supporting a platform. Extending outwardlyfrom the offshore structure 11 is a carriage boom 51 supported bybracing member 52 which is attached to the carriage boom 51 and to acollar 53 arranged rotatably on the support member 12.

A landing ramp 54 is carried dependingly by lines or structural members55' from the structure 11 and extends outwardly therefrom to provide afree end 5542.

Supported by a counterweight line 56 which extends over spaced-apartpulleys 57 and 58 is a carriage 59 provided with pulleys 6t) and 61 overwhich the line 56 extends, the carriage boom 51 being provided with acrosshead 62 on its free end in order to carry the carriage 59 in astable, nonrotating condition. Arranged on the top of the carriage 59and operatively connected to the line 3 3 56 is a brake 63 which may beoperated by a man in the carriage 59. Connected tothe lower end of thecarriage 59 is a rope or line 31 which extends through a port 36 in alanding ramp 37 and over a pulley or sheave or fair lead 33 on the crewboat 32 and is connected to the winch 34 on the motor or engine 35.

Extending outwardly from the offshore structure. 11 is an elongatedmember 64 to which is attached a line or flexible member 65, the freeend of which is led over .a sheave 66 (hidden by the structure in FIG. 2but shown in FIG. 3) into carriage 59 permitting slewing carriage boom51 from landing ramp 54 to extended postion. Another slewing line 67 isprovided, one end of which is attached to ramp 54 and extends overpulley 68 on structure 11 and over pulley 69 attached to boom 51 intocarriage 59. .Line 67 permits slewing the carriage boom 51 from extendedposition to a position adjacent the landing ramp 54.

The carriage boom 51 is connected to the offshore structure 11 by pivotmeans 510 which allows the carriage boom 51-to pivot in a horizontalplane and to bring the carriage 59 adjacent the free end 55a of the ramp54 so that when the carriage is'in its top position, the carriage floorand ramp floor are in the same plane. The slewing arrangement isintended to position the carriage clear of theplatform during ascent anddescent.

Referring specifically to FIG. 4, the counterweight 19 is provided witha plurality of circumferentially spacedapart fins 70, 71, 72, and 73,the fins 70 to 73, inclusive, being provided with ports 74, 75,76, and77. The lowjer end of the counterweight 19 is provided with a valve cage78 in which a valve 79 is carried. The lower end of the counterweight 19also has a valve seat 86 on which the valve 79 is designed to seat.

illustration purposes on fins 71 only. Plates 82, when' used, increasethe damping eflFect of fins 70 to 73, inelusive.

. The counterweight guide pipe 18 suitably contain-s a body of fluid orliquid which may be air, water, other gases, oil, or othernoncompressible liquid such as mercury and the like which is used fordamping downward movement of the counterweight 19. Also, it may be opento the sea by means of side ports or it may be closed to the sea.

Referring now to FIG. 5, the carriage 28 of FIG. 1 and carriage 59 ofFIG. 2 is provided with a quick release mechanism generally designatedby numeral 90 comprised of brackets 91, 92, 93, and 94 attached to thebottom of carriage 28. Brackets 91 to 94, inclusive, are provided withaligned openings 95, 96, 97, and 98 through which a pin 99 is inserted.A compression .spring .100 is mounted between and bears with its endsagainst brackets 92 and 93 and against plate 101 attached to pin 99 andurges pin 99 into the position shown in the'drawing. Pin 99 is connectedby pivot 102 to a yoke 103 which in turn has an actuation member orhandle 104 which extends into carriage 28. By depressing the handle 104,the pin 99 is moved to the right allowing the eye means 105 connected toflexible line 31-to be attached to or released from the carriage 28.Thus, if an operator in the carriage 28 wishes to be freed of line 31,he depresses the handle 194 which retracts pin 99 causing quick releaseof the carriage 28.

The present invention operates 'as follows:

In all instances in accordance with the several figures of the drawing,the effective pull of the counterweight 19 exerted on the carriage isgreater than the effective counterpull of the carriage plus a normaloperating load such that the normal position for the carriage is in theup position as shown in the several figures of the drawing. Thus, theweight of the counterweight may be greater than, or, as explained below,some fraction of, the weight of the 4 carriage plus the loading whichmay be placed thereon. For example, in FIG. 1 where the counterweightand carriage are connected directly by lines 24, the weight of thecounterweight is greater than that of the carriage and any loadingthereon. In FIG. 2 where the counterweight is connected to thecarriage'through a double-purchase line 56, giving the counterweight a 2to 1 mechanical advantage, the counterweight may have a weight greaterthan about one-half of the total weight of the carriage and its loading.Triple, quadruple, or any greater number of purchase lines such as 56may be employed. Where multiple or plural purchase lines are employed,it is important that the counterweight must not exceed the weight of thecarriage plus any loading or the brake 63 will be ineffective inslowingand stopping the carriage since application of the brake changes amultiple purchase line in efiectto a single purchase line. For slowingand stopping to be efiected,qthe singlepurchase pull must be less thanthe Weight of the carriage and load.

. When the crew boat approaches, a member of the operating crew of thecrew boat 32 will catch the dangling line 31 and-thread it through port36 and overthe pulley 33 and attach same to the winch 34 or connect theline attached to' the Winch 34. 'By operating the motor 35,

' the carriage is pulled downwardly to the landing ramp 37. It is thenpossible for personnel to step ofi or on to. the carriage and release ofthe line from the winch 34 allows the carriage to travel immediately andrapidly upwardtoward' the ofishore structure 11. In the case of FIG. 1,the shock absorber such as compression springs 39 lessens the, shock onhitting the ramp whereas in FIG. 2,,the. man being carried upwardlyoperates the brake as may be desired. 1 a

The-present inventionis quite important and useful 'in that whenthecarriage or cage is released from the deckofthe boat, the counterweightaccelerates down- ,wardly at an equal or greater rate than the boatmoves upwardly until itenters the body of liquid and the liquid thendecelerates'the counter weight travel by the fluid damping the motion.Withthe counterweight producing the desired damping action, the cage isbrought to rest under the ramp by. the use of shock absorbers such ascompression springs or brakes to absorb the small remaining impactmomentum of the carriage.

'An important feature of the invention is the diflferential damping tocontrol deceleration. This is accomplished by providing the fins 70 to73 with openings or ports 74 to 77 which either may all be open or partmay be closed or some ofthe ports may be closed by plates 82. -Asthe-ball valve 79 closes-buoyancy of the counterweight 19 isincreasedand as the fins 70 to 73 each sequentially enter the fluid or liquid inthe guide pipe 18 a stepped increase in the deceleration effect isobtained, thecounterweight 19 increasing progressively in buoyancy as itsinks into the water in pipe 18.

It is contemplated that deceleration may also be controlled by changingthe viscosity and/or density of the liquid or fluid in guide pipe 18.For example, half or part of the fluidv may be oil and the other half orpart may be water, the drag force changing with viscosityand the buoyantforce changing with density. i

vA basic criterion of the counterweight operation is that it mustaccelerate the loaded. carriage faster than the pitching and heavingacceleration of the boat in order to prevent the boat from slamming intothe bottom of the carriage. Thus, the carriage is pulled downwardly tothe boat by use of. the boats winch, or capstan, and the line isconnected to the boat. Since the counterweight before damping is capableof producing a carcarriage will always stay taut and any relativevertical .motion between the carriage and the boat will be the amount ofline taken up on the winch, or capstan. Thus the carriage may be easeddown to the deck of the boat without danger-of impact or slamming.Ascent of the carriage from the boat is accomplished by easing oil onthe line connecting with the capstan or winch or by rapidly disengagingthe carriage from the boat or line and allowing the counterweight andsubsequent damping to control the carriages upward motion.

In accordance with the present invention, the marine transfer assemblyis quite safe in the upward direction should the line to the boat breakor be released accidentally or on purpose. The use of two cables resistsrotation and also provides a safe feature in that one cable, if broken,would not cause the carriage to fall.

Donward velocity of the counterweight causes the ball check valve toclose when it enters into the liquid and blanks oif the flow areathrough the pipe, causing greater damping of the counterweights downwardmotion than open pipe because of greater drag and buoyancy. The finsprovide restriction to flow of fluid in the annular space between theguide pipe and the counterweight, causing additional damping. Byproviding cover plates on the ports of the fins, as has been shown inFIG. 4, additional flow restriction and regulation of the amount ofdamping may be provided. The counterweight damping sufliciently slowsdown the carriage in gradual steps for stability and comfort as itsapproaches the ramp walkway such that the shock absorbers absorb smallfinal impact momentum and bring the carriage to rest.

The ports 81 immediately above the fins 7-9 allow flow of water into thepipe to equal ze the static head on the ball valve 79 and causes thenonbuoyant ball valve to drop when the counterweight is at rest. Duringupward travel of the counterweight, the ball valve is open, providingadditional flow area for upward motion and with the valve 79 open thereis less buoyancy and more efiective counterweight to support thecarriage.

The present invention has been successfully used in transferringpersonnel between a crew boat and an offshore platform.

The nature and objects of the present invention having been completelydescribed and illustrated, what we wish to claim as new and useful andsecure by Letters Patent is:

1. A device for transferring objects between an upper and a lower marinestation having different relative heights above the sea, at least thelower of said stations freely floating upon the surface of the sea,which comprises a carriage, first pulley means attached to said lowerstation, first cable means passing over said pulley means and attachedto the bottom of said carriage, cantilever support means depending fromsaid upper station and extending laterally therefrom, second pulleymeans mounted on the projecting extremity of said support means, thirdpulley means mounted near the inward portion of said support means,second cable means attached to the upper portion of said carriage andextending over and partially around said second and said third pulleymeans, and counterweight means attached to and depending from saidsecond cable means below said third pulley means, of sufiicient weightto exert an effective pull greater than the combined weight of saidcarriage and said objects by an amount suflicient to impart an upwardacceleration to said carriage at least equal to the vertical movement ofsaid lower station which is induced by wave action, and furthercomprising a guide means for said counterweight vertically disposedbeneath said third pulley means and extending for a distance at leastequal to the length of travel of said counterweight and at leastpartially filled with a damping liquid, said second cable means being ofsuch length that the counterweight is suspended above the damping liquidand enters said damping liquid only after the carriage has risen abovethe lower station a distance greater than the vertical movement of thestation as a result of the action of the sea.

2. An apparatus in accordance with claim 1 wherein said counterweight iselongated in form, and further comprising damping vanes attached ataxially-spaced points on the outer periphery of said counterweight.

3. An apparatus in accordance with claim 2 wherein said counterweight isof hollow, cylindrical form and wherein the lower portion thereof is inthe form of a valve seat, and further comprising a ball valve movablysupported on said counterweight below said lower portion and adapted toseal said valve seat.

4. An apparatus in accordance with claim 3 wherein said cantileversupport is rotatably attached to said upper station, and furthercomprising a plurality of pulley means attached to the upper portion ofsaid carriage, the second cable means passing through said pulley meansand being attached to the projecting extremity of said cantileversupport means, and brake means interposed between two of said pluralityof pulley means for controlling the rate of ascent of said carriage.

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